Countershading is a form of camouflage where an animal's body is darker on the upper (dorsal) side and lighter on the lower (ventral) side. This adaptive coloration helps to counteract the effects of natural light and shadow, making the animal appear a more uniform colour and thus harder for predators or prey to detect.

A. Hibernation is a state of winter dormancy where an animal slows its metabolism to survive cold temperatures and food scarcity; it is a physiological and behavioral adaptation, not a form of adaptive colouration.

B. Aestivation is similar to hibernation but occurs during hot, dry periods to conserve water and energy; it is a form of dormancy, not colouration.

C. Migration is the regular, seasonal movement of animals from one place to another, usually in search of food or to better breeding grounds; it is a behavioral adaptation related to movement, not body colouration.